how to destroy game objects with a raycast and health?

Hello everyone. I am having trouble destroying a gameobject with health throught a raycast. I can destroy the game object directly after a touch. But I want the gameobject to have health. How can I lower the health from the game object throught a raycast? Here is the code to clarify:

 public class RaycastTest : MonoBehaviour {
 
     private Ray ray;
     private RaycastHit hit;
     private EnemyHealth EnemyHealthScript;
     // Use this for initialization
     void Start () {
         EnemyHealthScript = (EnemyHealth)FindObjectOfType(typeof(EnemyHealth));
     }
     
     // Update is called once per frame
     void Update () {
 
         if (Input.touchCount > 0)
         {
             ray = Camera.main.ScreenPointToRay(Input.GetTouch(0).position);
             if (Physics.Raycast(ray, out hit))
             {
                 if (hit.collider.tag == "Enemy")
                 {
                     EnemyHealthScript.LowerHealth();
                 }

The: EnemyHleathScript.LowerHealth() is giving me trouble and giving me a NullReferenceExepction. Here is the enemy health script:

 public class EnemyHealth : MonoBehaviour {
 
     public int Health = 100;
 
     // Use this for initialization
     void Start()
     {
         Destroy(this.gameObject, 23);
     }
     // Update is called once per frame
     void Update () {
 
         if(Health <=0){
             Destroy(this.gameObject);
         }    
     }
    public void LowerHealth()
     {
         Health -= 50;
     }

Cheers and thanks in advance!